int cmd_cat(FILE * f, int argc, char ** argv)
{
struct fs_dirent entry;
struct fs_file * fp;
int i;
if (argc < 2)
return SHELL_ERR_ARG_MISSING;
if (argc > 2)
return SHELL_ERR_EXTRA_ARGS;
if (!fs_dirent_lookup(argv[1], &entry)) {
fprintf(f, "invalid file: \"%s\"\r\n", argv[1]);
return SHELL_ERR_ARG_INVALID;
}
fp = entry.fp;
for (i = 0; i < fp->size; ++i) {
int c = fp->data[i];
fputc(c, f);
}
return 0;
}
/* This is the main workhorse for the virtual filesystem. Given a start point and
* a path string, it resolves the path into a directory entry. This is simply a
* matter of looping through the path (seperated at '/', of course), and reading
* the successive directory entries and inodes (see vfs_dirent_lookup and
* vfs_dirent_readinode). The one thing it needs to pay attention to is the case
* of traversing backwards up through a mount point. */
struct dirent *fs_do_path_resolve(struct inode *start, const char *path, int sym_start_level, int *result)
{
vfs_inode_get(start);
ASSERT(start);
if(!*path)
path = ".";
if(result) *result = 0;
struct inode *node = start;
struct dirent *dir = 0;
struct inode *nextnode = 0;
while(node && *path) {
if(dir) {
vfs_dirent_release(dir);
dir = 0;
}
char *delim = strchr(path, '/');
if(delim != path) {
nextnode = 0;
const char *name = path;
size_t namelen = delim ? (size_t)(delim - name) : strlen(name);
dir = fs_dirent_lookup(node, name, namelen);
if(!dir) {
if(result) *result = -ENOENT;
vfs_icache_put(node);
return 0;
}
if(delim) {
nextnode = fs_dirent_readinode(dir, true);
if(namelen == 2 && !strncmp("..", name, 2)
&& node->id == node->filesystem->root_inode_id) {
// Traverse back up through a mount.
vfs_inode_get(nextnode->filesystem->point);
struct inode *tmp = nextnode;
nextnode = nextnode->filesystem->point;
vfs_icache_put(tmp);
} else if(nextnode) {
if((*result = fs_resolve_iter_symlink(&dir, &nextnode, sym_start_level))) {
vfs_icache_put(node);
return 0;
}
nextnode = fs_resolve_mount(nextnode);
if(!nextnode) {
vfs_icache_put(node);
return 0;
}
}
}
vfs_icache_put(node);
node = nextnode;
}
path = delim + 1;
}
if(nextnode)
vfs_icache_put(nextnode);
return dir;
}
int cmd_rm(FILE * f, int argc, char ** argv)
{
struct fs_dirent entry;
if (argc < 2)
return SHELL_ERR_ARG_MISSING;
if (argc > 2)
return SHELL_ERR_EXTRA_ARGS;
if (!fs_dirent_lookup(argv[1], &entry)) {
fprintf(f, "invalid file: \"%s\"\r\n", argv[1]);
return SHELL_ERR_ARG_INVALID;
}
fs_file_unlink(&entry);
return 0;
}
int cmd_js(FILE * f, int argc, char ** argv)
{
struct fs_dirent entry;
char * script;
int len;
if (argc < 2)
return SHELL_ERR_ARG_MISSING;
if (argc > 2)
return SHELL_ERR_EXTRA_ARGS;
if (fs_dirent_lookup(argv[1], &entry)) {
script = (char *)entry.fp->data;
len = entry.fp->size;
} else {
script = argv[1];
len = strlen(argv[1]);
}
return js(f, script, len);
}
/* note that this function doesn't actually delete the dirent. It just sets a flag that
* says "hey, this was deleted". See vfs_dirent_release for more details. An important
* aspect is that on unlinking a directory, it does unlink the . and .. entries, even
* though the directory won't actually be deleted until vfs_dirent_release gets called
* and the last reference is released. */
static int do_fs_unlink(struct inode *node, const char *name, size_t namelen, int rec)
{
if(!vfs_inode_check_permissions(node, MAY_WRITE, 0))
return -EACCES;
struct dirent *dir = fs_dirent_lookup(node, name, namelen);
if(!dir)
return -ENOENT;
struct inode *target = fs_dirent_readinode(dir, true);
if(!target || (rec && S_ISDIR(target->mode) && !fs_inode_dirempty(target))) {
if(target)
vfs_icache_put(target);
vfs_dirent_release(dir);
return -ENOTEMPTY;
}
atomic_fetch_or_explicit(&dir->flags, DIRENT_UNLINK, memory_order_release);
if(S_ISDIR(target->mode) && rec) {
do_fs_unlink(target, "..", 2, 0);
do_fs_unlink(target, ".", 1, 0);
}
vfs_icache_put(target);
vfs_dirent_release(dir);
return 0;
}
/* This function returns the directory entry associated with the name 'name' under
* the inode 'node'. It must be careful to lookup the entry in the cache first. */
struct dirent *fs_dirent_lookup(struct inode *node, const char *name, size_t namelen)
{
if(!vfs_inode_check_permissions(node, MAY_READ, 0))
return 0;
if(!S_ISDIR(node->mode))
return 0;
if(node == current_process->root && !strncmp(name, "..", 2) && namelen == 2)
return fs_dirent_lookup(node, ".", 1);
mutex_acquire(dirent_cache_lock);
rwlock_acquire(&node->lock, RWL_WRITER);
struct dirent *dir = vfs_inode_get_dirent(node, name, namelen);
if(!dir) {
dir = vfs_dirent_create(node);
dir->count = 1;
strncpy(dir->name, name, namelen);
dir->namelen = namelen;
int r = fs_callback_inode_lookup(node, name, namelen, dir);
if(r) {
dir->count = 0;
vfs_dirent_destroy(dir);
rwlock_release(&node->lock, RWL_WRITER);
mutex_release(dirent_cache_lock);
return 0;
}
vfs_inode_get(node);
vfs_inode_add_dirent(node, dir);
} else {
if(atomic_fetch_add(&dir->count, 1) == 0) {
fs_dirent_remove_lru(dir);
vfs_inode_get(node);
}
}
rwlock_release(&node->lock, RWL_WRITER);
mutex_release(dirent_cache_lock);
return dir;
}
/* This is possibly the lengthiest function in the VFS (possibly in the entire kernel!).
* It resolves a path until the last name in the path string, and then tries to create
* a new file with that name. It requires a lot of in-sequence checks for permission,
* existance, is-a-directory, and so forth. */
struct inode *fs_path_resolve_create_get(const char *path, int flags, mode_t mode, int *result, struct dirent **dirent)
{
// Step 1: Split the path up into directory to create in, and name of new file.
int len = strlen(path) + 1;
char tmp[len];
memcpy(tmp, path, len);
char *del = strrchr(tmp, '/');
if(del)
*del = 0;
char *dirpath = del ? tmp : ".";
char *name = del ? del + 1 : tmp;
if(dirpath[0] == 0)
dirpath = "/";
if(dirent)
*dirent = 0;
if(result)
*result = 0;
// Step 2: Resolve the target directory.
struct inode *dir = fs_path_resolve_inode(dirpath, flags, result);
if(!dir)
return 0;
if(!S_ISDIR(dir->mode)) {
if(result) *result = -ENOTDIR;
return 0;
}
// Step 3: Try to look up the file that we're trying to create.
struct dirent *test = fs_dirent_lookup(dir, name, strlen(name));
if(test) {
// If it was found, return it and its inode.
if(dirent)
*dirent = test;
struct inode *ret = fs_dirent_readinode(test, true);
if(ret)
ret = fs_resolve_mount(ret);
if(!ret) {
if(dirent)
*dirent = 0;
if(result)
*result = -EIO;
vfs_dirent_release(test);
} else {
if(!dirent)
vfs_dirent_release(test);
if(result)
*result = 0;
}
vfs_icache_put(dir);
return ret;
}
// Didn't find the entry. Step 4: Create one.
if(!vfs_inode_check_permissions(dir, MAY_WRITE, 0)) {
if(result) *result = -EACCES;
vfs_icache_put(dir);
return 0;
}
if(dir->nlink == 1) {
if(result) *result = -ENOSPC;
vfs_icache_put(dir);
return 0;
}
uint32_t id;
// Step 4a: Allocate an inode.
int r = fs_callback_fs_alloc_inode(dir->filesystem, &id);
if(r) {
if(result) *result = r;
vfs_icache_put(dir);
return 0;
}
// Step 4b: Read in that inode, and set some initial values (like creation time).
struct inode *node = vfs_icache_get(dir->filesystem, id);
if(!node) {
vfs_icache_put(dir);
if(result) *result = -EIO;
return 0;
}
node->mode = mode;
node->length = 0;
node->ctime = node->mtime = time_get_epoch();
vfs_inode_set_dirty(node);
// If we're making a directory, create the . and .. entries.
if(S_ISDIR(mode)) {
// Create . and ..
if(fs_link(node, node, ".", 1, true))
r = -EPERM;
if(fs_link(node, dir, "..", 2, true))
r = -EMLINK;
}
// Step 4c: Create the link for the directory entry to the inode.
r = fs_link(dir, node, name, strlen(name), false);
if(result)
*result = !r ? 1 : r;
if(dirent && !r) {
*dirent = fs_dirent_lookup(dir, name, strlen(name));
if(!*dirent && node) {
vfs_icache_put(node);
vfs_icache_put(dir);
if(result)
*result = -EIO;
return 0;
}
}
vfs_icache_put(dir);
return r ? 0 : node;
}
